5:16 a.m.
Hi,
I am new to Drools and do some experiments on it, and encountered on a
problem which can't solve for a last few days, so maybe someone can explain
what I am doing wrong?
I will probably explain my problem with example. Lets say we have a
collection of letters like 'a', 'b', 'c', 'a',
'd', 'e', 'c'. And I want to
report all letters that are duplicated, but only once providing a number of
duplication. In other words, for each letter which is duplicated I need to
do a report by saying 'Letter X is duplicated N times.
My idea was to create cardinality collection for letters which is a
collection of POJOs Tuple where first is letter and second is cound (first
and second are properties). I created a function for it createCardinality(
Collection letters ) which returns such cardinality info and tried something
like:
when
Something( $letters: collectionOfLetters )
Tuple( $letter: first, $count: second > 1 ) from collect( Tuple() from
createCardinality( $letters ) )
then
System.out.println( "Letter "+letter+" is duplicated
"+$count+"
times" )
But I am reported (at least it looks like this) about the problems with my
function createCardinality(). Maybe I misunderstood something about usage of
FROM?
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6:22 a.m.
createCardinality must return a Collection. I think the simplest way of
solving your problem is to write a simple class LetterCounter implementing
the counting and a DRL function extracting the collection of Tuples from the
LetterCounter:
public class LetterCounter extends HashMap<Character,Integer> {
public static Set<Map.Entry<Character,Integer>> counterSet(
Collection<Character> l ){
return new LetterCounter( l ).entrySet();
}
public LetterCounter( Collection<Character> chars ){
super();
for( Character c: chars ){
Integer count = get( c );
put( c, count == null ? 1 : count + 1 );
}
}
}
rule "count"
when
$t: Something( $l: collectionOfLetters )
Map.Entry( $key: key, $val: value > 1 ) from LetterCounter.counterSet(
$l )
then
System.out.println( "letter " + $key + ": " + $val );
end
-W
On 18 December 2010 12:16, AleBu <aleboo(a)gmail.com> wrote:
Hi,
I am new to Drools and do some experiments on it, and encountered on a
problem which can't solve for a last few days, so maybe someone can explain
what I am doing wrong?
I will probably explain my problem with example. Lets say we have a
collection of letters like 'a', 'b', 'c', 'a',
'd', 'e', 'c'. And I want to
report all letters that are duplicated, but only once providing a number of
duplication. In other words, for each letter which is duplicated I need to
do a report by saying 'Letter X is duplicated N times.
My idea was to create cardinality collection for letters which is a
collection of POJOs Tuple where first is letter and second is cound (first
and second are properties). I created a function for it createCardinality(
Collection letters ) which returns such cardinality info and tried
something
like:
when
Something( $letters: collectionOfLetters )
Tuple( $letter: first, $count: second > 1 ) from collect( Tuple()
from
createCardinality( $letters ) )
then
System.out.println( "Letter "+letter+" is duplicated
"+$count+"
times" )
But I am reported (at least it looks like this) about the problems with my
function createCardinality(). Maybe I misunderstood something about usage
of
FROM?
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8 a.m.
Am I missing something or can't this be achieved purely "in rule":-
rule "Letter counter"
salience -100
when
Letter( $c: character )
not LetterCount( character == $c )
List( $s : size > 1 ) from collect( Letter( character == $c ) )
then
LetterCount lc = new LetterCount();
lc.setCharacter($c);
lc.setDuplications($s);
insert(lc);
end
rule "Totals"
salience 0
when
LetterCount($c : character, $s : duplications);
then
System.out.println("Letter " + $c + " has " + $s + "
duplications"
end
2010/12/18 Wolfgang Laun <wolfgang.laun(a)gmail.com>
createCardinality must return a Collection. I think the simplest way
of
solving your problem is to write a simple class LetterCounter implementing
the counting and a DRL function extracting the collection of Tuples from
the LetterCounter:
public class LetterCounter extends HashMap<Character,Integer> {
public static Set<Map.Entry<Character,Integer>> counterSet(
Collection<Character> l ){
return new LetterCounter( l ).entrySet();
}
public LetterCounter( Collection<Character> chars ){
super();
for( Character c: chars ){
Integer count = get( c );
put( c, count == null ? 1 : count + 1 );
}
}
}
rule "count"
when
$t: Something( $l: collectionOfLetters )
Map.Entry( $key: key, $val: value > 1 ) from LetterCounter.counterSet(
$l )
then
System.out.println( "letter " + $key + ": " + $val );
end
-W
On 18 December 2010 12:16, AleBu <aleboo(a)gmail.com> wrote:
>
> Hi,
> I am new to Drools and do some experiments on it, and encountered on a
> problem which can't solve for a last few days, so maybe someone can
> explain
> what I am doing wrong?
> I will probably explain my problem with example. Lets say we have a
> collection of letters like 'a', 'b', 'c', 'a',
'd', 'e', 'c'. And I want
> to
> report all letters that are duplicated, but only once providing a number
> of
> duplication. In other words, for each letter which is duplicated I need to
> do a report by saying 'Letter X is duplicated N times.
> My idea was to create cardinality collection for letters which is a
> collection of POJOs Tuple where first is letter and second is cound (first
> and second are properties). I created a function for it createCardinality(
> Collection letters ) which returns such cardinality info and tried
> something
> like:
> when
> Something( $letters: collectionOfLetters )
> Tuple( $letter: first, $count: second > 1 ) from collect( Tuple()
> from
> createCardinality( $letters ) )
> then
> System.out.println( "Letter "+letter+" is duplicated
"+$count+"
> times" )
>
> But I am reported (at least it looks like this) about the problems with my
> function createCardinality(). Maybe I misunderstood something about usage
> of
> FROM?
> --
> View this message in context:
>
http://drools-java-rules-engine.46999.n3.nabble.com/How-to-use-a-result-o...
> Sent from the Drools - User mailing list archive at Nabble.com.
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
_______________________________________________
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8:10 a.m.
Looks somewhat different to me; originally there's a fact containing a
Collection of letters, not individual Letter() facts, each with its own
character. Therefore, you don't have the fact for the initial pattern.
-W
2010/12/18 Michael Anstis <michael.anstis(a)gmail.com>
Am I missing something or can't this be achieved purely "in
rule":-
rule "Letter counter"
salience -100
when
Letter( $c: character )
not LetterCount( character == $c )
List( $s : size > 1 ) from collect( Letter( character == $c ) )
then
LetterCount lc = new LetterCount();
lc.setCharacter($c);
lc.setDuplications($s);
insert(lc);
end
rule "Totals"
salience 0
when
LetterCount($c : character, $s : duplications);
then
System.out.println("Letter " + $c + " has " + $s + "
duplications"
end
2010/12/18 Wolfgang Laun <wolfgang.laun(a)gmail.com>
createCardinality must return a Collection. I think the simplest way of
> solving your problem is to write a simple class LetterCounter implementing
> the counting and a DRL function extracting the collection of Tuples from
> the LetterCounter:
>
> public class LetterCounter extends HashMap<Character,Integer> {
> public static Set<Map.Entry<Character,Integer>> counterSet(
> Collection<Character> l ){
> return new LetterCounter( l ).entrySet();
> }
> public LetterCounter( Collection<Character> chars ){
> super();
> for( Character c: chars ){
> Integer count = get( c );
> put( c, count == null ? 1 : count + 1 );
> }
> }
> }
>
> rule "count"
> when
> $t: Something( $l: collectionOfLetters )
> Map.Entry( $key: key, $val: value > 1 ) from
> LetterCounter.counterSet( $l )
> then
> System.out.println( "letter " + $key + ": " + $val );
> end
>
> -W
>
>
> On 18 December 2010 12:16, AleBu <aleboo(a)gmail.com> wrote:
>
>>
>> Hi,
>> I am new to Drools and do some experiments on it, and encountered on a
>> problem which can't solve for a last few days, so maybe someone can
>> explain
>> what I am doing wrong?
>> I will probably explain my problem with example. Lets say we have a
>> collection of letters like 'a', 'b', 'c', 'a',
'd', 'e', 'c'. And I want
>> to
>> report all letters that are duplicated, but only once providing a number
>> of
>> duplication. In other words, for each letter which is duplicated I need
>> to
>> do a report by saying 'Letter X is duplicated N times.
>> My idea was to create cardinality collection for letters which is a
>> collection of POJOs Tuple where first is letter and second is cound
>> (first
>> and second are properties). I created a function for it
>> createCardinality(
>> Collection letters ) which returns such cardinality info and tried
>> something
>> like:
>> when
>> Something( $letters: collectionOfLetters )
>> Tuple( $letter: first, $count: second > 1 ) from collect( Tuple()
>> from
>> createCardinality( $letters ) )
>> then
>> System.out.println( "Letter "+letter+" is duplicated
"+$count+"
>> times" )
>>
>> But I am reported (at least it looks like this) about the problems with
>> my
>> function createCardinality(). Maybe I misunderstood something about usage
>> of
>> FROM?
>> --
>> View this message in context:
>>
http://drools-java-rules-engine.46999.n3.nabble.com/How-to-use-a-result-o...
>> Sent from the Drools - User mailing list archive at Nabble.com.
>> _______________________________________________
>> rules-users mailing list
>> rules-users(a)lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
_______________________________________________
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8:40 a.m.
Fair point :)
I took "collection" to mean some letters rather than "Collection".
2010/12/18 Wolfgang Laun <wolfgang.laun(a)gmail.com>
Looks somewhat different to me; originally there's a fact
containing a
Collection of letters, not individual Letter() facts, each with its own
character. Therefore, you don't have the fact for the initial pattern.
-W
2010/12/18 Michael Anstis <michael.anstis(a)gmail.com>
Am I missing something or can't this be achieved purely "in rule":-
>
> rule "Letter counter"
> salience -100
> when
> Letter( $c: character )
> not LetterCount( character == $c )
> List( $s : size > 1 ) from collect( Letter( character == $c ) )
> then
> LetterCount lc = new LetterCount();
> lc.setCharacter($c);
> lc.setDuplications($s);
> insert(lc);
> end
>
> rule "Totals"
> salience 0
> when
> LetterCount($c : character, $s : duplications);
> then
> System.out.println("Letter " + $c + " has " + $s + "
duplications"
> end
>
> 2010/12/18 Wolfgang Laun <wolfgang.laun(a)gmail.com>
>
> createCardinality must return a Collection. I think the simplest way of
>> solving your problem is to write a simple class LetterCounter
>> implementing
>> the counting and a DRL function extracting the collection of Tuples from
>> the LetterCounter:
>>
>> public class LetterCounter extends HashMap<Character,Integer> {
>> public static Set<Map.Entry<Character,Integer>> counterSet(
>> Collection<Character> l ){
>> return new LetterCounter( l ).entrySet();
>> }
>> public LetterCounter( Collection<Character> chars ){
>> super();
>> for( Character c: chars ){
>> Integer count = get( c );
>> put( c, count == null ? 1 : count + 1 );
>> }
>> }
>> }
>>
>> rule "count"
>> when
>> $t: Something( $l: collectionOfLetters )
>> Map.Entry( $key: key, $val: value > 1 ) from
>> LetterCounter.counterSet( $l )
>> then
>> System.out.println( "letter " + $key + ": " + $val );
>> end
>>
>> -W
>>
>>
>> On 18 December 2010 12:16, AleBu <aleboo(a)gmail.com> wrote:
>>
>>>
>>> Hi,
>>> I am new to Drools and do some experiments on it, and encountered on a
>>> problem which can't solve for a last few days, so maybe someone can
>>> explain
>>> what I am doing wrong?
>>> I will probably explain my problem with example. Lets say we have a
>>> collection of letters like 'a', 'b', 'c',
'a', 'd', 'e', 'c'. And I want
>>> to
>>> report all letters that are duplicated, but only once providing a number
>>> of
>>> duplication. In other words, for each letter which is duplicated I need
>>> to
>>> do a report by saying 'Letter X is duplicated N times.
>>> My idea was to create cardinality collection for letters which is a
>>> collection of POJOs Tuple where first is letter and second is cound
>>> (first
>>> and second are properties). I created a function for it
>>> createCardinality(
>>> Collection letters ) which returns such cardinality info and tried
>>> something
>>> like:
>>> when
>>> Something( $letters: collectionOfLetters )
>>> Tuple( $letter: first, $count: second > 1 ) from collect( Tuple()
>>> from
>>> createCardinality( $letters ) )
>>> then
>>> System.out.println( "Letter "+letter+" is duplicated
"+$count+"
>>> times" )
>>>
>>> But I am reported (at least it looks like this) about the problems with
>>> my
>>> function createCardinality(). Maybe I misunderstood something about
>>> usage of
>>> FROM?
>>> --
>>> View this message in context:
>>>
http://drools-java-rules-engine.46999.n3.nabble.com/How-to-use-a-result-o...
>>> Sent from the Drools - User mailing list archive at Nabble.com.
>>> _______________________________________________
>>> rules-users mailing list
>>> rules-users(a)lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>
>>
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users(a)lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>>
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
_______________________________________________
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3:02 p.m.
The approach with "pure rule" is working too. I just was not capable to think
in this "rule" way, so thanks for hint!
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11:25 a.m.
Hi,
[offtopic]
Thanks for quick response! It is always nice when project has an active and
friendly community. This is a sign of healthy project itself :)
[/offtopic]
My function was returning a collection. It seems that I made an error in
import of the function. I had some debug, info, etc static methods in the
class and they were imported with import function ...* and it worked, so I
expected that adding public static createCountMap(...) into the same class
will solve it too, but somehow I needed to declare it explicitly.
Also, having the same code in Drools file in function declaration is not
working when I use java 5 syntax, so I just rewrote it with java 1.4 syntax
and it works fine too. If there is such a restriction, then it for sure
missed in official documentation
http://downloads.jboss.com/drools/docs/5.1.1.34858.FINAL/drools-expert/ht....
So, that were all my problems were :).
Thanks again for response!
I also can see another approach for solving the problem in the thread, so I
will play with it too - it looks interesting for me. Thinking in the
declarative drools like style requires some brain restructuring. It is like
moving from imperative to functional programming. And speaking of functional
approach - It reminds me about Scala and question here is:
Can Scala be used as one of the dialects in the future? Are there any plans
or thinkings or wishes in the "wish-list" for it? :}
--
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12:24 p.m.
On 18 December 2010 18:25, AleBu <aleboo(a)gmail.com> wrote:
Hi,
[offtopic]
Thanks for quick response! It is always nice when project has an active and
friendly community. This is a sign of healthy project itself :)
[/offtopic]
My function was returning a collection.
If it returns a Collection<Tuple> you should be able to use
when
Something( $letters: collectionOfLetters )
Tuple( $letter: first, $count: second > 1 ) from createCardinality(
$letters )
then
System.out.println( "Letter "+letter+" is duplicated
"+$count+"
times" )
end
"from collect" generates a Collection<X> from individial X's; from
<Collection-expression> inspects elements coming from a collection.
Please note that better help can be obtained by showing all of the relevant
code and the error messages.
-W
It seems that I made an error in
import of the function. I had some debug, info, etc static methods in the
class and they were imported with import function ...* and it worked, so I
expected that adding public static createCountMap(...) into the same class
will solve it too, but somehow I needed to declare it explicitly.
Also, having the same code in Drools file in function declaration is not
working when I use java 5 syntax, so I just rewrote it with java 1.4 syntax
and it works fine too. If there is such a restriction, then it for sure
missed in official documentation
http://downloads.jboss.com/drools/docs/5.1.1.34858.FINAL/drools-expert/ht...
.
So, that were all my problems were :).
Thanks again for response!
I also can see another approach for solving the problem in the thread, so I
will play with it too - it looks interesting for me. Thinking in the
declarative drools like style requires some brain restructuring. It is like
moving from imperative to functional programming. And speaking of
functional
approach - It reminds me about Scala and question here is:
Can Scala be used as one of the dialects in the future? Are there any plans
or thinkings or wishes in the "wish-list" for it? :}
--
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http://drools-java-rules-engine.46999.n3.nabble.com/How-to-use-a-result-o...
Sent from the Drools - User mailing list archive at Nabble.com.
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5089
days inactive
5089
days old
7 comments
3 participants
participants (3)
-
AleBu -
Michael Anstis -
Wolfgang Laun